The need for data backup becomes more evident as people become more dependent on their computers. Typically, entire computer hard discs can be backed up and restored when necessary. Selective restoration, however, such as the restoration of a particular file or directory, is typically more difficult. Where millions of files are backed up, selective restoration of identified files or directories typically result in poor performance, taking hours to restore a requested file. It would be desirable to improve the performance for selective restoration of data.